Package of flexible material, particularly for sterilisable food products

The present invention refers to a package of flexible material particularly suitable for containing food products in a liquid or viscous state or in a solid state with preserving liquid, destined to undergo heat treatments in an autoclave, such as jams, fruit juices and the like. However, the package according to the invention can also be used to to contain granular or solid products not necessarily of an edible type.

To remain in the sector of the liquid, sterilizable food products, at which the invention is aimed particularly, these products are currently packaged in hermetically closed cans or aluminium trays.

These packages hold various drawbacks which range from the relatively high costs to the complexity of the processes for manufacturing and filling the packages, to the difficulties in opening them.

Object of the present invention is to overcome the aforementioned drawbacks by providing a package of flexible material that is simple and cheap to produce, as well as easy to open.

Another object of the invention is to provide such a package that is able to guarantee the absolute sterility of the products contained therein.

These objects are achieved with the package according to the invention, which has the characteristics listed in appended independent claim <b>1</b>.

Advantageous embodiments of the invention are described in the dependent claims.

Essentially, the package of flexible material according to the invention, having a parallelepiped box shape, has on one face an opening that is closed by a peelable sheet or patch heat-sealed along the perimeter of the opening.

Normally, the material of the flexible package is multilayered and comprises at least one inner layer of aluminium acting as a barrier or another barrier layer, such as a layer of polyester coated with silicon or aluminium dioxide, and likewise the material of the flexible closure patch is multilayered and comprises a peelable inner layer such as to allow a seal of the easy-open type.

In particular, the sealing of the patch to the perimeter of the opening provided in the package takes place along a track that is disposed astride the edge of said opening, so that the heat of the heat-sealing causes a softening of the inner layer of the patch, which “runs” onto the edge of the opening, covering the edge of the layer of aluminium.

In this manner, any contact between the liquid or viscous product contained in the package and the aluminium layer, which could cause oxidation or corrosion, is avoided and the maintenance of the sterile conditions inside the package is ensured.

The flexible package is advantageously obtained from a continuous web which is die-cut in advance at regular distances to obtain the abovementioned openings closed by a patch and is sent to a forming mandrel which can be of the form and fill type, that is, around which the package is formed and filled with product.

In particular, the package according to the invention has four longitudinal seals of the fin-seals type, or even inside-to-inside seals, at the four longitudinal edges of the package, seals which serve to give the package a stiff consistency, one of them also serving to close the web longitudinally, forming a tube.

The package is then completed with two transversal seals and by folding thereof to form a gusset.

In the position of use of the formed package, the above mentioned longitudinal seals are disposed horizontally, forming protruding bottom and top edges, which stiffen the package and allow it to remain in a stable, upright position, with the peelable patch disposed on the upper face.

By way of example, the flexible film of the package according to the invention consists, advantageously, of four layers thus arranged from the outside in: a first layer of cast polypropylene (CPP), of heat-sealing biaxially oriented polypropylene (BOPP) or of heat-sealing polyethylene terephthalate; a second layer of aluminium; a third layer of polyethylene terephthalate or of nylon; a fourth layer of cast polypropylene.

The film of the window-closing patch, on the other hand, can be three-layered comprising, again from the outside in: polyethylene terephthalate, aluminium, cast or peelable polypropylene.

Further characteristics of the invention will be made clearer by the detailed description that follows, referring to a purely exemplifying and therefore non limiting embodiment thereof, illustrated in the appended figures, wherein:

<figref idrefs="DRAWINGS">FIG. 1</figref> is an axonometric view of a package according to the invention, shown in the position of use, with a possible closing-again lid;

<figref idrefs="DRAWINGS">FIG. 2</figref> is a top plan view of the package of <figref idrefs="DRAWINGS">FIG. 1</figref>, without the lid;

<figref idrefs="DRAWINGS">FIG. 3</figref> is a section taken along the line III-III of <figref idrefs="DRAWINGS">FIG. 2</figref>;

<figref idrefs="DRAWINGS">FIG. 4</figref> is an enlargement of the detail indicated with the letter A in <figref idrefs="DRAWINGS">FIG. 3</figref>;

<figref idrefs="DRAWINGS">FIGS. 5 to 8</figref> show diagrammatically successive steps in the manufacturing process of the package according to the invention.

With reference to said figures, and for now in particular to <figref idrefs="DRAWINGS">FIG. 1</figref>, reference numeral <b>1</b> designates as a whole a package according to the invention, particularly for sterilizable food products in a liquid or semi-liquid state, possibly incorporating solid pieces.

The package <b>1</b> has a parallelepiped box shape and has a (rectangular) base <b>2</b>, a top wall <b>3</b>, a front wall <b>4</b>, a back wall <b>5</b> and two side walls <b>6</b> and <b>7</b>.

On the top wall <b>3</b> a rectangular opening or window <b>8</b> is formed, which is closed by a peelable sheet or patch <b>9</b>, in the way that will be better described later.

Peripherally to the base <b>2</b> and to the top wall <b>3</b> there is a respective protruding edge <b>10</b>, obtained by sealing edges of the film making up the package, as will be described later, and serving to give it stiffness and stability.

Of course, in an alternative embodiment the edge <b>10</b> may be absent.

A possible manufacturing process for the package according to the invention will now be described with reference to <figref idrefs="DRAWINGS">FIGS. 5 to 8</figref>, to be understood as purely schematic. In fact, in said figures, and in particular in <figref idrefs="DRAWINGS">FIG. 6</figref>, the step of forming the window <b>8</b> and of closing it with the patch <b>9</b> is shown when the package is practically already formed and only the closure thereof is lacking. In fact, the windows <b>8</b> are advantageously die cut on a web of sheet material at regular distances and closed by the patches <b>9</b> before forming the package, that is, before the representation shown in <figref idrefs="DRAWINGS">FIG. 5</figref>, in which the web of material has been closed to form a tube and shown diagrammatically already cut to the right length to form the package <b>1</b>.

As shown in <figref idrefs="DRAWINGS">FIG. 1</figref>, four longitudinal seals <b>11</b> of the fin-seal type, in which inner edges of the film are brought into contact and sealed to each other, are made on the web of material, which is made to advance along a mandrel, normally disposed vertically. One of these longitudinal seals <b>11</b>, shown in bold in <figref idrefs="DRAWINGS">FIG. 5</figref> to distinguish it from the others, closes the web of sheet material to form a tube.

A bottom transverse seal <b>12</b> is then made (<figref idrefs="DRAWINGS">FIG. 6</figref>), which closes the tube at the bottom, followed by a gusset fold <b>14</b> (<figref idrefs="DRAWINGS">FIG. 7</figref>) and lastly by a further top transverse seal <b>13</b> and by a subsequent gusset fold <b>15</b> (<figref idrefs="DRAWINGS">FIG. 8</figref>) to close the package.

In the practice, if the mandrel around which the packages <b>1</b> are formed is of the form and fill type, in which the package is filled during the forming, when the transverse seal <b>13</b> is made to close the package, the bottom transverse seal <b>12</b> is made at the same time on the package immediately following, which is then separated by cutting it from the preceding one.

The formed package is then placed in the position of use as shown in <figref idrefs="DRAWINGS">FIG. 1</figref>, wherein the abovementioned longitudinal seals <b>11</b> form the top and bottom protruding peripheral edges <b>10</b> of the package <b>1</b>, with the two gusset folds <b>14</b> and <b>15</b> which are disposed to form the respective side walls <b>6</b> and <b>7</b>.

With reference now particularly to <figref idrefs="DRAWINGS">FIGS. 1 to 4</figref>, the method of application of the patch <b>9</b> to close the opening <b>8</b> is better described.

As shown by the area in grey on <figref idrefs="DRAWINGS">FIGS. 1 and 2</figref>, the patch <b>9</b> is sealed peelably to the top wall <b>3</b> of the package <b>1</b> along a sealing track <b>20</b> which is disposed astride the peripheral edge of the opening <b>8</b>. In this manner, the heat to which the area of the patch <b>9</b> is subjected during the heat-sealing causes the softening of the material in the area of the sealing track <b>20</b> not overlying the wall <b>3</b> beneath and said material covers the inner edge of the opening <b>8</b>.

This situation is schematised, in an exaggerated manner, in the enlarged section of <figref idrefs="DRAWINGS">FIG. 4</figref>, where the flexible film of the package <b>1</b> is shown as a laminate with four layers and the film of the peelable patch <b>9</b> as a laminate with three layers.

In particular, by way of example, working from the outside in, and thus from thee top to the bottom with reference to <figref idrefs="DRAWINGS">FIG. 4</figref>, the film of the package comprises a first layer <b>31</b> of cast polypropylene (CPP), of heat-sealing biaxially oriented polypropylene (BOPP) or of heat-sealing polyester (PET); a second layer <b>32</b> of aluminium; a third layer <b>33</b> of polyester or of nylon and a fourth layer <b>34</b>, again of cast polypropylene.

The film of the patch <b>9</b>, on the other hand, comprises, again from the outside in, that is from the top to the bottom, a first layer <b>91</b> of polyester, a second layer <b>92</b> of aluminium and a third layer <b>93</b> of peelable cast polypropylene.

As shown diagrammatically in <figref idrefs="DRAWINGS">FIG. 4</figref>, the melting of the layer <b>93</b> of CPP of the patch <b>9</b> during the heat-sealing produces an “overflow” of this material onto the inner edge of the opening <b>8</b>, and in particular the covering of the layer of aluminium <b>32</b>, preventing the contact of the content of the package <b>1</b> with the edge of the layer of aluminium, and thus preventing possible oxidations or corrosions, which would harm the sterility of the content of the package.

As stated previously, in fact, the package according to the invention is particularly suitable to contain sterilisable products, namely products which, after the packaging, can be subjected to heat treatment in an autoclave.

Therefore, the materials of the flexible films used for the package <b>1</b> and for the patch <b>9</b> are chosen so as to withstand high sterilisation temperatures.

If the package does not have to be subjected to heat treatments, that is if it is destined to contain non sterilisable products, polyethylene can be used for the various layers of films instead of polypropylene or of polyester.

<figref idrefs="DRAWINGS">FIG. 1</figref> shows diagrammatically how the opening of the package <b>1</b> takes place by raising and by puling an edge <b>25</b> of the patch <b>9</b> and by removing said patch thanks to the peelability of the heat seal along the track <b>20</b>.

Once the patch <b>9</b> has been removed, the contents of the package <b>1</b> can be consumed even by taking them directly from the package, for example using a spoon.

Optionally, a lid <b>40</b> to cover the package <b>1</b> can be provided on the top wall <b>3</b> where the patch <b>9</b> is provided, for reasons of hygiene, and possibly to close the package again in the event of a partial use of its contents.

The lid <b>40</b> shown in <figref idrefs="DRAWINGS">FIG. 1</figref> consists of a rectangular wall reproducing the shape of the top wall <b>3</b> of the package <b>1</b>, with a downward-facing peripheral edge <b>41</b>, which surrounds the protruding upper edge <b>10</b> of the package.

The seal of the lid is ensured by two opposite facing tongues <b>42</b> (only one can be seen in <figref idrefs="DRAWINGS">FIG. 1</figref>) which are inserted in the respective fan folds <b>14</b> and <b>15</b> provided at the side walls <b>6</b> and <b>7</b> of the package.

The lid <b>40</b> can be made of cardboard, of plastic or of other materials. It could possibly be made of a heat-shrinkable plastic material that adheres on the outside to the upper peripheral edge <b>10</b> of the package.

It is clear, however, that the invention is not limited to the particular embodiment previously described and illustrated in the appended figures, but numerous modifications of detail within the reach of a person skilled in the art can be made thereto without thereby departing from the scope of the invention, as set forth in the appended claims.